Drawing and method of and medium for making the same



Dec. 10, 1940. M, D. MNTOSH 2,224,269

DRAWING AND METHOD OF AND MEDIUM FOR MAKING THE SAME Filed Deo. 4, 1957 ATTO EYS I Patented Dec. 10,1940

UNITED STATES DRAWING AND METHOD F AND MEDIUM FOR MAKING THE SAME Maurice D. McIntosh; Cleveland, Olio, assignor to Louis S. Sanders, Cleveland, Ohio Application December 4, 1937, Serial No. 178,105

18 Claims.

'I'his invention relates as indicated to drawings suitable for camera copy and the like and to method of and medium for making the same.

Shaded or wash drawing copy, as now prepared, consists of various tones of at grays, composed of minutely dispersed black and white, such as gray paint, and cannot be successfully directly reproduced as line engravings. Such copy requires treatment by the half tone process,

which, in effect, translates the flat shades of gray into screen formations of solid blacks andwhites which are equivalent in tone value to the shades of gray. These screen formations are primarily series of geometrically spaced isolated 16 squares of solid black. In light values of half tone shading, the squares are surrounded by a relatively large amount of white space and as the tone value increases, the proportion of white space decreases until it disappears, resulting in 0 solid black. In other words, the original isolated squares increase in size with increasing tone value, progressing through the various screen formations until they completely overlap or merge into each other to form solid black. 'I'he dependent solely on the size of the squares.

The present invention has, as its primary object, the production of camera copy consisting .of various half tone screen formations in solid black and white and of any desired tone value, and suitable for` direct reproduction as line engravings, without treatment by the half tone process.

Other objects of the invention are the provision of a medium for use in making such camera copy and methods of making or preparing such medium.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly' pointed out in the claims, the annexed drawing and the following description setting forth in detail certain means and one mode of 45 carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in which the principle of the inventionv may be used.

In said annexed drawing:

Fig. 1 is a fragmentary perspective view illustrating the first stage in the manufacture of themedium of the present invention;` Fig. 2 is a fragmentary plan view of a shadow dot or print-- tone value or relation of black and white is thus (Cl. Li1-41) shadow dot or printing plate of Fig. 2 in position to transfer the ink thereon to the sensitized sheet of Fig. 1; Fig. 4 is a cross-sectional view of the assembled elements shown in Fig. 3; Fig. 5 is 5 a view similar to Fig. 4, but showing the printing plate removed; Fig. Sis a fragmentary top plan view, on an enlarged scale, of the sheet shown in Fig. 5; Fig. 7 is a view similar to Fig.

6, but showing a development of only those porlo tions of the sensitized gelatin surface which are exposed through the shadow dot openings in the varnish print; Figs. 8, 9, 10 and 11 are views similar to Fig. 7, but showing progressively darker tones produced by gradual increase in the 15 time of development; Fig. 12 is a cross-sectional view, taken on the line |2-I2 of Fig. 8.

Referring more particularly to the drawing and especially to Fig. 1, I represents a sheet of ordinary hard-sized white drawing board or zo paper, to which is applied a thin lm 2 of gelatin or other gelatinous material, such as albumen, casein, glue and the like. The sheet is then sensitized" by floating it, gelatin side down, for about 15 seconds in a 20% solution of ammonium molybdate. The term sensitizedl is here used in a special sense to designate the provision of a ilm on the sheet bearing a chemical or substance which is initially substantially invisible, but which iscapable of being rendered a0 visible or developed by chemical means. 'This permits the solution to penetrate only the gelatin film. The excess solution on the surface of the sheet is removed by blotting or by means of rollers and the sheet permitted to dry.

A printing plate 3 is then prepared having a multiplicity of square openings 4 therein, which are of a size, and spaced. from each other in a manner similar to the highlight dots of an ordinary halftone positive. Such openings, in actual 40 practice, are extremely small and spaced very closely together, Vbut the size and spacing are greatly enlarged in the presentI drawing, for purposes of clarity. A lm 5 of ink-of a transparent or translucent varnish of Waterproof type is then applied to the plate 3 in such a manner that the ink covers the entire surface of the plate, with the exception of the openings 4.

'I'he film 5 is then transferred directly to the 50 entire sensitized gelatin film 2 of the sheet l, in the manner shown in Figs. 3 and '4, that is, by applying the plate 3, inked side down, to the lm 2 of the sheet. Instead of using a flat printing plate, a cylindrical or roller type of printing device having Iopenings therein may be used to apply a film of ink to the nlm 2.

'Ihe plate 3 is then removed leaving a sheet,

which is the medium of the present invention, and consisting, as shown in Fig. 5 of the sheet I, the sensitized gelatin film 2 and a transparent film 5 of varnish, which coats and protects the entire surface of the iilm.2 with the exception of the small square dots corresponding to the openings 4 of the plate. In other words, the sensitized gelatin surface of the sheet is exposed only through the shadow dot openings in the varnish print.

This medium is then employed by the artist as a drawing surface, on which he may secure any highlight or shading effects he desires by merely applying a' suitable developer for the required period of time, as by means of a brush. the development being terminatedgby applying a blotter to such dots or otherwise removing the developing solution from such dots. Where paper, sensitized with a 20% ammonium molybdate solution is used as the drawing medium, a solution of stannous chloride may be employed as a developer.

If the artist desires a very light value of halftone shading, as shown in Fig. 7, he will apply the developer to the portion or portions of the sheet on which such tone is desired, leaving the 30 developer on the sheet-for a short length of time,

' i. e., about iive seconds, after'which he stops further development by means of a blotter, as described. The development, in this case, is confined to the areas of the fllm 2 which are exposed through the varnish covering of the sheet, the remaining portions of the film being protected from the action of the developer solution by the varnish. In other words, development of the film 2 can occur only through the openings in the 40 varnish coating of the sheet. Since molybdenum 'compounds are immediately reduced by stannous chloride to black molybdenum oxide, the development, in this case, is represented by a reduction l of the ammonium molybdate in the lm 2 to black 45 molybdenum oxide. The developed dots in Fig. 7

' are therefore solid black, but such solid black is represented in this, and in Figs. 8 to 11 inclusiv by means of cross-hatching.

If a somewhat darker value of halftone shading 50 is desired, as shown in Fig. 8, the developer solu- -tion is permitted to remain on the sheet for a somewhat longer period, i. e., about thirty seconds. .This causes development of the small areas shown in Fig. '7, and represented in Fig. 8 by the 55 dotted lines, and in addition, the developer solution diffuses uniformly in all directions out into the gelatin under the varnish, resulting in the larger developed dots or areas, shown in Fig, 8. Although a portion of this development takes 60 place under the varnish coating 5, the entire developed dot is visible, due to the transparency of the varnish. Moreover, due to the fact that the diffusion of the developer solution in the gelatin is absolutely uniform in all directions, the

65 original square shape of the dot is maintained in the progressive enlargement of such dots.

Figs. 9, 10 and ll represent darker values of halftone shading. which are obtained by permitting the developer solution to remain on the sheet 70 for progressively longer periods. In Fig. 9, the shaded areas cover half the area of the sheet, the dots being in contiguity with eachother at their corners. The developer in this instance, has been permitted to remain on the sheet about 75 one minute. In Fig. 10, the shaded areas cover more than half the area of the sheet, the dots overlapping eachother at the corners. The developer. in this instance, has been permitted to remain on the sheet about one and one-half minutes. In Fig. 11, the shaded areas completely overlap each other to form solid black. The developer, in this instance, was permitted to remain on the sheet about two minutes. It is apparent from these figures that 'the development proceeds from the rst tone dot to solid black in about two minutes. This affords ample time for control of tone values.

The progression of tone value from the first developed highlight dot to the darkest reverse" and black, achieved through enlarging the square units of the screen formation, is a counterpart of halftone progression.

After the drawing is completed, it may be used without further treatment for any desired purpose, such, for example, as camera copy for the direct production of line engravings. If desired, the varnish coating may be removed by means of an organic solventwhich is non-miscible with Water, as, for example, carbon tetrachloride, benzene, etc., and Awhich will not affect the drawing.

Instead of ammonium molybdate and stannous chloride, various other combinations of chemical l compounds may be employed to produce the desired color reaction, it being only necessary that the developer-and the sensitizer (chemical compound in the gelatin) be colorless lor of light actinic color and the product -of reaction of the two be black,` brown, red or a non-actinic color. Among such combinations may be listed the following:

Sensltizer cobalt, bismuth, and tin compounds Alkali solutions, reducing agents, Silver compounds and soluble suldcs In most instances, the chemical compounds in the above combinations are interchangeable, that is to say, the developer can be placed in the gelatin and the sensitizer used as the developing agent or solution.

Although the-foregoing description has been coniined to the enlargement of square dots, it is to be understood that the invention is not limited to dots of such shape, and that dots of circular and other forms may be used.

Other modes of applying the principle' of my invention may be employed instead of the one explained, change being made as regards the means and the steps herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I therefore particularly point out and distinctly claim as my invention:

l. 'I'he method of preparing a drawing which comprises applying to the surface of a sheet a film containing a chemically-developable compound, applying over `said film a coating of a transparent or translucent substance insoluble in the developer for said compound, said coating 'being applied in such a manner as to leave exposed a pattern of geometrically-spaced dots consisting of said chemically-developable substance, `Y

and then developingportions of said pattern.

2. The method of preparing a drawing which lm of a transparent or translucent material insoluble in the developer for said compound, said lm being applied in such a manner as to leave exposed a halftone pattern containing said chemically-developable compound, and then developing portions of said pattern to form an image.

Q 3. In a method of making drawings, the ,steps of providing a drawing surface having a plurality of spaced substantially invisible areas, and

then rendering selected areas .visible in varying proportions of extent of areatherebytoproduce visible lines, tones and shades.

4. An artists drawing surface consisting of a continuous invisible coating having a plurality of spaced exposed areas, said areas being capable of being rendered visible by application of a developer thereto and of beingprogressively enlarged in accordance with the duration of contact of said developer with said areas.

5. In a method of making drawings, the steps of providing a drawing surface having a plurality of spaced substantially invisible areas, and then rendering selected areas visibleiri varying proportions of surface dimensional extent byapplication to said areas of a developer for varying periods, thereby to produce visible lines, tones and shades. V i

6. A medium for use in preparing drawings suitable for use as camera copy consisting ofl a sheet having a surface bearing anim of chemically-developable material and a permanent coating of a transparent ortranslucent varnish covering said lm with the exception of a multiplicity of spaced areas, said varnish being impenetrable by the developer for` said material.

7. The method of making a medium for use in preparing drawings suitable for use as camera copy which consists of applying a permanent coating of a chemically-developable substance to the surface of a sheet, and then applying a coating of a transparent orV translucent substance impenetrable by the developer for. said "firstnamed substance to selected portions of said rst-named coating, whereby. those portions of the latter to which said second-named coating is not applied are exposed to immediate contact;

. ner as to leave exposed a multiplicity of spaced areas of said chemically-developable substance, whereby said spaced areas are capable of immediate development and of being brought to visibility by initial contact with such developer.

9. The method of making va medium for use in preparing drawings suitable for use" as camera copy, which consists of applying to selected portions of a sheet bearing a coating of a chemically-developable material, a coating of a transparent or translucent substance impenetrable by the developer for said material, whereby said` selected portions are developable to visibility through said last-named coating.

10. The method of making a medium for use in preparing drawings suitable for use as camera copy which consists of applying to a sheet bearing a coating of a `chemicaily-developable substance a coating of a transparent or translucent substance impenetrable by the developer chemically-developable substance, whereby that portion ofllthe latter surrounding said spaced areas is developable to visibility through said A last-named coating.

11. A E medium for use in preparing drawings suitable for use as camera copy consisting of a. sheet having a surface containing a film of. chemically-developable' material and a permanent coating of a'transparent or translucent material impenetrable by the developer for said firstnamed material covering selected portions of said film.

12. A medium for use in preparing drawings l`suitable for use as camera copy consisting `of a sheet having a surface bearing a iilm of chemi- K cally-developable material and a permanent coating of a transparent or translucent mate.-

rial impenetrable by thev developer for ysaid firstnamed material covering said film', with the exception of a multiplicity of uniformly. spaced dots.

13. The method of'preparing a drawing suitable for use as camera' copy which comprises applying a'developer for a desired interval of time lto selected, uniform sized exposedportions of' a medium bearing a film of chemically-developable material, saidv portions being exposed through a coating of transparent or translucent substance impenetrable by said developer, whereby said exposed portions are/ developed to Visible f areas of given size, and applying a developer for other desired intervals of time to other of said exposed portions of said film, whereby said lastnamed portions and contiguous, unexposed portions are developed to visible areas of different sizes.

14. The method of lmaking a drawing suitable for use as camera copywhich comprises applyng a developing -agent for varying intervals of time to selected, uniform-sized exposed portions of the chemically-developable material of' a medium having a lm of such material, said portions beingv'exposed through a coating of a trans- 'parent or translucent substance impenetrable by said developing agent, whereby said exposed portions and contiguous, unexpos'ed. portions are developed to visible areas having a size corresponding in direct proportion to the time of application of said developing agent.

15. A medium for use in preparing drawings Suitable for use as camera copyconsisting of a sheet having a surface containing a lm of a material of a color having no photographic value but capable of being chemically developed 'to a color having a photographic value, and a permanent coating of a transparent or translucent material impenetrable by the developer for said first-named material covering selected vportions of said lm.

16. A medium for use in, preparing drawings suitable for use as camera copy consisting of -.a sheet having a surface containing a lm of a rnaterial'of a color having no photographic value but capable of being chemically developed vto a color having a photographic value, and a permarient coating of a transparent or translucent varnish covering said film with the exception of a multiplicity of spaced areas, said varnish y being impenetrable by the developer forsaid rstnamed material.

17. A medium for use in preparing drawings suitable for use as camera copy consisting of asuitable for use as camera copy consisting of a sheet having a surface containing a continuous lm of a chemically-developable material and a coating of a transparent or translucent varnish covering said film with the exception of a 5 multiplicity of spaced areas, said varnish being' impenetrable by the developer for said iirstnamed material.

. MAURICE D. MciNTOSH. 

